The present invention relates to a water purification plant for purifying liquid by flotation clarification, in which pollution particles, or the impurities dissolved in the liquid and brought into a particle form by means of flocculation chemicals, are separated from the liquid to the purified, float to the top surface of the liquid and are then led on the surface into a slurry bed. The slurry bed is directed away into a sewer system or the like and the purified liquid is led through an intermediate bottom, or the like arranged in a lower part of clarification basin, into a lower space of the clarification basin or directly away for additional purification or consumption. When waste water is the liquid being purified, the purified water can be directed back to the environment.
The flotation method has proved to be the best and most efficient water purification method for chemically purifying lakes, rivers and other water reservoirs as well as iron-bearing and polluted groundwaters. Similarly, it is the most efficient chemical purification method for waste waters, especially when very difficult and complex industrial waste waters and preliminary and/or final purification stages of waste water is involved. concerned.
When purifying water or waste water, it is a prevailing fact that the constructions of the purification systems and basins are large and expensive. In cold climates, the purification system and basin have to be protected by means of normal heatable house structures.
In Finnish Patent Application No. FI 841591, a method for purifying a fluid by means of flotation clarification is described. In this method, the pollution particles, or the impurities dissolved in the fluid and brought into a particle form by means of flocculation chemicals, are separated from the fluid to the purified and led onto the surface of the fluid as a slurry bed. The slurry bed is led away into a sewer system or the like and the purified fluid is led via a bottom portion of the clarification basin through a bottom therein for consumption, or when waste water is involved, the purified fluid is directed e.g., back to the environment. In this method, the purified fluid flows down in the clarification basin after a runoff channel within the area of the entire clarification basin, including the basin region adjacent to the runoff channel, by means of an edge circulating around the clarification basin. The purified fluid flows from below the edge and the flow of the purified fluid is extremely uniform within the area of the entire clarification basin. The pollution particles rise up immediately and accumulate on the surface of the clarification basin in the entire clarification basin.